<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>style样式</title>
</head>
<body>
  <h2 id="con">I love JavaScript</H2>
  <p> JavaScript使网页显示动态效果并实现与用户交互功能。</p>
  <script type="text/javascript">
    var mychar= document.getElementById("con");
    mychar.style.color='333'
    mychar.style.backgroundColor='#ccc';
    mychar.style.width  = '300px';

  </script>
</body>
</html>